Skip to content
Math Calculators

Reverse Percentage Calculator

Verified formula Updated Jun 2026 Private — runs on your device

Enter details
%
Verified formula Private

Original amount

100.00

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Reverse Percentage Calculator

The Reverse Percentage Calculator works out your original amount in an instant. Enter final amount, percentage and change applied and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the final amount.
  2. Enter the percentage.
  3. Choose the change applied.
  4. Read off your original amount — the calculator updates automatically, with no button to press.

Worked example

For example, with final amount of 120, percentage of 2% and change applied of Was increased by, the original amount is 100.00.

Inputs used
Final amount 120
Percentage 2%
Change applied Was increased by
Results
Original amount 100.00

Results are estimates for educational use, not professional advice.

Key terms explained

Percentage
A number expressed as a fraction of 100, written with the % sign.

Frequently asked questions

For an increase, divide the final amount by (1 + percent ÷ 100). 120 after a 20% increase came from 100.

Divide the final price by (1 − percent ÷ 100). A price of 80 after a 20% discount was originally 100. Choose 'decreased by'.

Because the percentage applied to the original, not the final amount. Subtracting it from the final gives the wrong answer.

For removing tax or VAT from a total, finding pre-discount prices, or undoing any known percentage change.

Enter the final amount. Enter the percentage. Choose the change applied. Read off your original amount — the calculator updates automatically, with no button to press.

How to Calculate Percentages: The Complete Guide

Master every kind of percentage problem — finding a percentage of a number, percentage change, increases and decreases, working backwards, and the traps that catch people out — with clear examples.

4 min read

Related calculators